The table below shows current air quality concentrations at New Hampshire's air monitoring sites for two air pollutants:
ground-level ozone and particle pollution (fine particles). Full monitoring, reporting,
and forecasting for ozone occurs from March through September; monitoring and reporting of fine particles occurs year-round.
The information in the table is updated every hour and includes wind speed, wind direction, and outside temperatures (if
data are available). A map of monitoring site locations is shown at the right.

Ozone values are based on eight-hour running averages; Fine Particle values are based on twenty four-hour running
averages. If a complete-period average cannot be calculated, due to absence of data, the average is displayed
within square brackets (e.g., [ 31 ])

2.

Data in the table are based on real-time hourly averages for the time period ending at .
All real-time values are unofficial pending full quality assurance/quality control evaluation.

N/D indicates that the Site is enabled but the latest-period data are temporarily unavailable.

5.

N/R indicates that the Site is currently disabled.

6.

Grayed-out cells indicate that the parameter is not collected at the Site.

7.

Seasonal indicates that Ozone monitoring occurs from March through September at the site.

Ground-level Ozone
Ground-level ozone, more commonly called smog, is measured in parts per billion (ppb). The federal health based standard
for an 8-hour concentration is set at 70 ppb. Since ozone is a summertime pollutant, wintertime monitoring is limited and
no wintertime forecast is provided. Full monitoring, reporting, and forecasting for ozone occurs from March through September.

The EPA established a tighter 8-hour ozone standard in October of 2015 to better protect public health. The 8-hour standard
was lowered from 0.075 ppm to 0.070 ppm. For more information, please visit https://www.epa.gov/ozone-pollution.

Fine Particles
Fine particle pollution consists of both solid and liquid particles that are less than 2.5 microns in diameter (a micron
is a millionth of a meter). Particle concentrations are measured in micrograms per cubic meter (ug/m3). The federal
health based standard for a 24-hour concentration is set at 35 ug/m3. Monitoring and reporting of fine particles
occurs year-round.

The EPA has established tighter fine particle standards to better protect public health. In 2006 the standard was lowered
from 65 ug/m3 to 35 ug/m3. In 2012 the annual standard was lowered from 15.0 ug/m3 to 12
ug/m3. For more information, please visit https://www.epa.gov/pm-pollution.

Sulfur Dioxide
Sulfur dioxide (SO2) is a highly reactive gas which primarily comes from fossil fuel combustion at power plants
and other industrial facilities. Sulfur dioxide concentrations are measured in parts per billion (ppb). The federal health
based standard for 1-hour concentrations is set at 75 ppb. Monitoring and reporting of sulfur dioxide occurs year round.

EPA first set standards for sulfur dioxide in 1971. In June 2010 EPA established a 1-hour SO2 standard at 75
ppb to better protect public health. For more information, please visit https://www.epa.gov/so2-pollution.